Plating system

ABSTRACT

A plating system in which a plating process of a semiconductor substrate held by a wafer holder provided on the top of a plating tank is conducted while jetting the plating liquid upward from the lower side in the plating tank, wherein a plurality of nozzles for removing bubbles adhered on the surface of the semiconductor substrate are provided in the tank so that the plating liquid is jetted from the nozzles to the semiconductor substrate.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a plating system. More specifically, the present invention relates to a plating system suitable for a plating process of a semiconductor substrate.

[0003] 2. Description of the Prior Art

[0004]FIG. 4 is a diagram showing a prior art construction of a plating process.

[0005] As shown in FIG. 4, the prior art plating system has an inner tank 8, an outer tank 7, a wafer holder 6 and a reservoir 12.

[0006] The inner tank 8 is provided in its bottom surface with an anode electrode 9 and a jet port 15 for feeding a plating liquid to the inner tank 8.

[0007] To feed the plating liquid overflowed from the inner tank 8 to the reservoir 12, the outer tank 7 is provided in its bottom surface with a plating liquid discharge port 10 and a plating liquid return pipe 11. There are also provided a jet pump 13 for jetting the plating liquid reserved in the reservoir 12 to the inner tank 8 and a filter 14 for removing particles at jetting.

[0008] The wafer holder 6 is provided with a contact part 3 for passing an electric current to a wafer (device surface) 2 and can pass an electric current to the wafer (device surface) 2 while rotating and holding the wafer. The wafer (device surface) 2 held by the wafer holder 6 is contacted with the liquid level of the inner tank 8 in parallel.

[0009] In FIG. 4, the wafer holder 6 is lowered and the rotating wafer (device surface) 2 is contacted with a plating liquid (a liquid level 27). An electric current at film deposition is flowed to the contact part 3 and the anode electrode 9 to conduct a plating process. Bubbles 18 produced at the contact are adhered on the wafer (device surface) 2. Part of the bubbles adhered on the edge part periphery of the wafer (device surface) 2 is overflowed by a liquid current 19 to flow to the outer tank 7. The center part of the wafer (device surface) 2 is a stagnation region 20 of the liquid current 19. The flow rate is low so that the bubbles cannot be removed by a physical action.

[0010] The wafer (device surface) 2 in the state that the bubbles remain is subjected to a plating process. When conducting the plating process in such state, the uniformity at film deposition is lowered. The remaining bubbles are crushed to be particulate and are then taken into a plated film as a macro void and pit, resulting in lowering of the yield.

[0011] In the prior art plating system, as the method for contacting the wafer (device surface) with the plating liquid, a facedown method is used. Air between the wafer surface and the plating liquid level cannot be prevented from being included. Bubbles remain and are adhered on the wafer surface. In the plating tank, part of the bubbles is discharged outside of the plating tank by a physical external force by jet in the plating tank. In the center of the wafer surface contacted with the stagnation region 20 of the plating liquid level, the remaining and adhered bubbles cannot be removed completely from the wafer surface.

BRIEF SUMMARY OF THE INVENTION

[0012] Summary of the Invention

[0013] In a plating system in which a plating process of a semiconductor substrate held by a wafer holder provided on the top of a plating tank is conducted while jetting a plating liquid upward from the lower side in the plating tank, a plurality of nozzles for removing bubbles adhered on the surface of the semiconductor substrate are provided in the tank so that the plating liquid is jetted from the nozzles to the semiconductor substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The above-mentioned and other objects, features and advantages of this invention will become more apparent by reference to the following detailed description of the invention taken in conjunction with the accompanying drawings, wherein:

[0015]FIG. 1 is a block diagram showing the construction of a first specific example of a plating system according to the present invention;

[0016]FIGS. 2A to 2D are diagrams of assistance in explaining the operation of the first specific example;

[0017]FIG. 3 is a diagram showing the construction of a second specific example of the present invention; and

[0018]FIG. 4 is a diagram showing the construction of a prior art plating system.

DETAILED DESCRIPTION OF THE INVENTION

[0019] Specific examples of a plating system according to the present invention will be described below in detail with reference to the drawings.

[0020]FIGS. 1 and 2 are diagrams showing a first specific example of the present invention. These drawings show a plating system having an inner tank 8, an outer tank 7 provided so as to surround the inner tank 8 for receiving a plating liquid from the inner tank 8, a reservoir 12 for reserving the plating liquid in the outer tank, a plating liquid admission pipe 21 connecting the reservoir 12 and the inner tank 8, and a jet pump 13 provided on the plating liquid admission pipe 21 for jetting the plating liquid into the inner tank 8 in which a plating process of a semiconductor substrate 2 held by a wafer holder 6 provided on the top of the inner tank 8 is conducted while jetting the plating liquid upward from the lower side in the inner tank 8, wherein a plurality of nozzles 4, 5 for removing bubbles 18 adhered on the surface of the semiconductor substrate 2 are provided in the inner tank 8 so as to jet the plating liquid from the nozzles 4, 5 to the semiconductor substrate 2, and the plating liquid jetted from the nozzles 4, 5 is supplied from a split-flow pipe 22 provided to be branched from the plating liquid admission pipe 21.

[0021] Air operate valves 16, 17 are provided on the split-flow pipe 22. The air operate valves 16, 17 control discharge of the plating liquid of the nozzles 4, 5. The plating liquid jetted from the nozzles 4, 5 is jetted outward from the center of the semiconductor substrate.

[0022] Control means 25 for controlling the discharge timing of the nozzles 4, 5 is provided.

[0023] The first specific example will be described below in greater detail.

[0024] The construction of the first specific example will be described.

[0025] Referring to FIG. 1, the plating system of the present invention has an inner tank 8, an outer tank 7, a wafer holder 6 and a reservoir 12.

[0026] The inner tank 8 is provided in its bottom surface with an anode electrode 9 and a jet port 15 for feeding a plating liquid to the inner tank 8. There are provided nozzles 4, 5 which discharge the plating liquid to a wafer (device surface) 2 when the wafer (device surface) 2 held by the wafer holder 6 is contacted with the plating liquid in the inner tank 8. The nozzles 4, 5 are branched from a secondary side pipe 21 of a filter 14. Air operate valves 16, 17 control a discharge amount and a discharge timing. The numeral 25 denotes a controller for controlling the discharge amount and the discharge timing.

[0027] To feed the plating liquid overflowed form the inner tank 8 to the outer tank 7 to the reservoir 12, the outer tank 7 is provided in its bottom surface with a plating liquid discharge port 10 and a plating liquid return pipe 11. A jet pump 13 jets the plating liquid in the reservoir 12 through the filter 14 into the inner tank 8.

[0028] The construction of the wafer holder 6 will be described. The wafer holder 6 is provided with a contact part 3 for passing an electric current to the wafer (device surface) 2 and can pass an electric current to the wafer (device surface) 2 while rotating and holding the wafer. The wafer (device surface) 2 held by the wafer holder 6 is contacted with the liquid level of the inner tank 8 so as to be opposed.

[0029] Using FIGS. 1 and 2, the operation will be described.

[0030]FIG. 2A shows a state that while housing and holding the wafer in the wafer holder 6, there is no current carrying in the contact part 3 and the anode electrode 9 and the wafer holder 6 is at a top dead center.

[0031] The plating liquid is jetted from the jet port 15 of the inner tank 8 and is then overflowed to the outer tank 7 by the action of a liquid current 19.

[0032]FIG. 2B shows a state that the wafer holder 6 is lowered from the state of FIG. 2A to a bottom dead center and the wafer (device surface) 2 is contacted with the plating liquid in the inner tank 8. The instant that the plating liquid is contacted with the wafer (device surface) 2, a very small electric current is flowed to the contact part 3 and the anode electrode 9 to prevent seed film dissolution on the wafer (device surface) 2. When there is no current carrying and the wafer (device surface) 2 is contacted with the plating liquid, the seed film corroded by the plating liquid. The instant that the wafer (device surface) 2 is contacted with the plating liquid, an electric current smaller than that at film deposition is flowed.

[0033] When the wafer (device surface) 2 is contacted with the plating liquid, air in a gap between the liquid level of the inner tank 8 and the wafer (device surface) 2 is included. The instant that the wafer (device surface) 2 is contacted with the liquid level, the included air remains and is adhered as bubbles 18 on the wafer (device surface) 2.

[0034] Part of the bubbles remaining and adhered on the edge part of the wafer (device surface) 2 is easily removed by the liquid current 19 in the inner tank 8 and is overflowed to the outer tank 7. The vicinity of the center part of the wafer (device surface) 2 is a stagnation region 20 of the liquid current 19. The bubbles 18 are not removed by the liquid current 19.

[0035] To remove the bubbles, as shown in FIG. 2C, immediately after contacting the wafer (device surface) 2 with the plating liquid, an air operate valve 16 is opened only at an arbitrary set time. Using the secondary pressure of a jet pump 13, the plating liquid is discharged from the nozzle 5 provided on the inner tank 8 to the wafer (device surface) 2. Without flowing the electric current at film deposition, an electric current smaller than that of film deposition is flowed.

[0036] As shown in FIG. 2D, after the air operate valve 16 is closed and discharge of the plating liquid from the nozzle 4 is completed, an air operate valve 17 is opened. Using the secondary pressure of the jet pump 13, the plating liquid is discharged from the nozzle 4 to the wafer (device surface) 2 at an arbitrary set time.

[0037] Any sequence can be set such that the nozzles 4, 5 discharge the plating liquid immediately before starting film deposition, in film depositing (application of a high electric current at film deposition), or intermittently in synchronization with application of a low electric current.

[0038] When the plating liquid is discharged alternately from the nozzles 4, 5 to the wafer (device surface) 2 in the stagnation region 20, the center part of the wafer (device surface) 2 is a turbulent-flow region. The turbulent-flow is formed to remove the remaining and adhered bubbles at contact of the wafer (device surface) 2. After completing the sequence, the electric current at film deposition is flowed to conduct the plating process (film deposition process).

[0039] After removing the bubbles 18 on the wafer (device surface) 2, to conduct film deposition, any micro pit and micro void due to the influence of the bubbles 18 can be prevented from being caused, improving the yield.

[0040]FIG. 3 is a diagram showing a second specific example of the present invention. These drawings show a plating system having a plurality of nozzles 4, 5 provided in an inner tank 8 for discharging a plating liquid to a semiconductor device to remove bubbles 18 adhered on the surface of a semiconductor substrate, and nozzle discharge pumps 15, 15A supplying the plating liquid in a reservoir 12 to the nozzles 4, 5 wherein using the nozzle discharge pumps 15, 15A, the discharge amount of the plating liquid discharged from the nozzles 4, 5 is controlled.

[0041] The second specific example will be described below in greater detail using FIG. 3.

[0042] In the second specific example, using discharge pumps 26, 26A, the plating liquid is discharged from the nozzles 4, 5 to the wafer (device surface) 2. When the secondary pressure of the jet pump is used and the bubbles on the wafer (device surface) 2 cannot be removed in the first specific example, the discharge pumps 26, 26A of a flow rate variable type can set the flow rate corresponding to the bubble removal state. When the flow rate is optimized, the bubble removal performance can be further improved.

[0043] The numeral 28 denotes a controller for controlling the discharge amount and the discharge timing of the discharge pumps 26, 26A.

[0044] The plating system according to the present invention thus constructed can prevent any micro void and micro pit produced by taking the bubbles in the plating liquid into the plated film. The quality of the plated film can be maintained at a fixed level, thereby improving the yield of the plating process.

[0045] Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that the appended claims will cover any modifications or embodiments as fall within the true scope of the invention. 

What is claimed is:
 1. A plating system in which a plating process of a semiconductor substrate held by a wafer holder provided on the top of a plating tank is conducted while jetting a plating liquid upward from the lower side in said plating tank, wherein a plurality of nozzles for removing bubbles adhered on the surface of said semiconductor substrate are provided in said tank so that said plating liquid is jetted from said nozzles to said semiconductor substrate.
 2. The plating system according to claim 1, wherein said nozzles are constructed so that the plating liquid jetted from said nozzles is discharged outward from the center of said semiconductor substrate.
 3. A plating system having an inner tank, an outer tank provided so as to surround said inner tank for receiving a plating liquid from said inner tank, a reservoir for reserving the plating liquid in said outer tank, a plating liquid admission pipe connecting said reservoir and said inner tank, and a jet pump provided on said plating liquid admission pipe for jetting said plating liquid in said inner tank in which a plating process of a semiconductor substrate held by a wafer holder provided on the top of said inner tank is conducted while jetting said plating liquid upward from the lower side in said inner tank, wherein a plurality of nozzles for removing bubbles adhered on the surface of said semiconductor substrate are provided in said inner tank so that the plating liquid is jetted from said nozzles to said semiconductor substrate, and the plating liquid jetted from said nozzles is supplied from a split-flow pipe provided to be branched from said plating liquid admission pipe.
 4. The plating system according to claim 3, wherein air operate valves are provided on said split-flow pipe so as to control discharge of the plating liquid of said nozzles.
 5. A plating system having an inner tank, an outer tank provided so as to surround said inner tank for receiving a plating liquid from said inner tank, a reservoir for reserving the plating liquid in said outer tank, a plating liquid admission pipe connecting said reservoir and said inner tank, and a jet pump provided on said plating liquid admission pipe for jetting said plating liquid in said inner tank in which a plating process of a semiconductor substrate held by a wafer holder provided on the top of said inner tank is conducted while jetting said plating liquid upward from the lower side in said inner tank, comprising: a plurality of nozzles provided in said inner tank discharging said plating liquid to said semiconductor device to remove bubbles adhered on the surface of said semiconductor substrate; and nozzle discharge pumps supplying the plating liquid in said reservoir to said nozzles, wherein using said nozzle discharge pumps, the discharge amount of the plating liquid discharged from said nozzles is controlled.
 6. The plating system according to claim 3 or 5, further comprising control means for controlling the discharge timing of said nozzles.
 7. The plating system according to claim 1, 3 or 5, wherein when discharging the plating liquid from said nozzles, an electric current smaller than that at a plating process is flowed to protect a seem film. 